1. Technical Field
The present disclosure relates generally to telecommunications and more particularly to a wireless telecommunications system.
2. Description of the Related Art
FIG. 1 depicts a schematic diagram of a portion of a typical wireless telecommunications system designated generally as 10. System 10 serves a number of wireless terminals 22 and 24 that are situated within a geographic area. System 10 comprises wireless switching center 12 that is connected to a number of base stations 14.sub.i and that is also coupled to local and long distance telephone networks 16. Wireless switching center 12 is responsible for, among other things, routing or "switching" calls from and to wireless terminals or, alternatively, between a wireless terminal and a wireline terminal connected to wireless system 10, via local and/or long distance telephone networks 16.
The geographic area serviced by wireless system 10 is partitioned into a number of spatially distinct areas called cells. As depicted in FIG. 1, each cell 20.sub.i is schematically represented by a hexagon. In practice, however, each cell 20.sub.i usually has an irregular shape that depends, for example, on the topography of the terrain serviced by system 10. Typically, each cell 20.sub.i contains a corresponding base station 14.sub.i. Base station 14.sub.i comprises antennas and radios to communicate with wireless terminals 22 and 24. Each base station 14.sub.i also comprises transmission equipment to communicate with wireless switching center 12.
In designing system 10, engineers allocate a limited number of frequency channels to each base station 14.sub.i using well known techniques. Base stations 14.sub.i communicate with wireless terminals over these frequency channels. Thus, the number of base stations limits the potential capacity of system 10 for processing calls to and from wireless terminals.
As wireless telecommunications has increased in popularity, designers have developed techniques for increasing the capacity of these wireless telecommunications systems. One common technique is to reduce the size of each cell by "splitting" existing cells into multiple cells. Some designers have even suggested reducing the size of cells to provide so called "microcells" that service very small geographic regions.
The public has resisted use of microcells for several reasons. First, many people fear that electromagnetic radiation from base stations could cause health problems. Further, real estate in populated areas is typically expensive and accounts for about half the cost of the base station. Thus, it is a difficult and expensive proposition to split cells to increase capacity of a wireless telecommunications system.